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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

EXTREME PROCESSORS FOR EXTREME PROCESSING : STUDY OF MODERATELY PARALLEL PROCESSORS

Bangsgaard, Christian, Erlandsson, Tobias, Örning, Alexander January 2005 (has links)
Future radars require more flexible and faster radar signal processing chain than commercial radars of today. This means that the demands on the processors in a radar signal system, and the desire to be able to compute larger amount of data in lesser time, is constantly increasing. This thesis focuses on commercial micro-processors of today that can be used for Active Electronically Scanned Array Antenna (AESA) based radar, their physical size, power consumption and performance must to be taken into consideration. The evaluation is based on theoretical comparisons among some of the latest processors provided by PACT, PicoChip, Intrinsity, Clearspeed and IBM. The project also includes a benchmark made on PowerPC G5 from IBM, which shows the calculation time for different Fast Fourier Transforms (FFTs). The benchmark on the PowerPC G5 shows that it is up to 5 times faster than its predecessor PowerPC G4 when it comes to calculate FFTs, but it only consumes twice the power. This is due to the fact that PowerPC G5 has a double word length and almost twice the frequency. Even if this seems as a good result, all the PowerPC´s that are needed to reach the performance for an AESA radar chain would consume too much power. The thesis ends up with a discussion about the traditional architectures and the new multi-core architectures. The future belongs with almost certainty to some kind of multicore processor concept, because of its higher performance per watt. But the traditional single core processor is probably the best choice for more moderate-performance systems of today, if you as developer looking for a traditional way of programing processors.
172

Implementation study of radar signal processing Using SIMD architectures

Ekström, Mikael, Westerberg, Martin January 2006 (has links)
The aim of this pro ject was to evaluate the use of SIMD array architectures in radar signal processing. This has been done by implementing one of the most demanding parts of the radar signal processing chain for airborne radar on the CSX600 architecture devel- oped by Clearspeed Technologies. The CSX600 architecture is a SIMD processor with 96 processing elements which can be arranged either as a linera array or as a ring. The QR- decomposition, which was the part chosen for implementation, is the most performance demanding part of the STAP stage. In order to create a relevant test case the well known RT STAP benchmark from Mitre Corporation has been used. Two different algorithms for performing QR-decompositions have been implemented and verified. In both cases it has been concluded that either longer (> ≈256) or shorter (< ≈32) processor array lengths would, in general, yield a higher utilization ratio. The FLOP count and utiliza- tion has been measured for both algorithms, and it has been concluded that at least eight CSX600 processors are needed to meet the real-time demand of the benchmark.
173

A peptide array for bovine-specific Kinome analysis : comparative analysis of bovine monocytes activated by TLR4 and TLR9 agonists

Jalal, Shakiba 22 September 2008 (has links)
As phosphorylation represents the pivotal mechanism for regulation of biological processes, kinases belong to one of the most biologically significant enzyme classes. The development of analytical techniques for characterization of kinase activity, in particular at a global scale, is a central priority for proteomic and cell biology researchers. In order to facilitate global analysis of cellular phosphorylation, a new paradigm of microarray technology which focuses on analysis of total cellular kinase activity, kinome, has emerged in the past few years. As the specificity of many kinases is dictated primarily by recognition of residues immediately surrounding the site of phosphorylation a logical methodology is to employ peptides representing these immediate sequences as experimental substrates. Microarray chips carrying hundreds of such substrate targets have been developed for human kinome analysis, however, lack of similar tools for species outside research mainstream has limited kinome analysis in these species.<p> Based on sequence alignment of orthologous phosphoproteins from mammalian species, conservation of amino acid identity is reported to be 80 %. Accordingly, the potential exists to utilize phosphorylation sequence databases to extrapolate phosphorylation sites in other species based on their genomic sequence information. Peptides representing these proposed phosphorylation sites can then be utilized as substrates to quantify the activity of the corresponding kinase. Based on these principles, a bovine microarray of 300 unique peptide targets was constructed. The bovine phosphorylation targets were selected to represent a spectrum of cellular events but with focus on processes related to innate immunity. Initial application and validation of the bovine peptide arrays was carried out for kinome analysis of bovine blood monocytes stimulated with either lipopolysaccharide (LPS) or CpG-ODNs; ligands for Toll-like receptors (TLR) 4 and 9, respectively. The arrays confirmed activation of the known TLR signaling pathway as well as identifying receptor-specific phosphorylation events. Phosphorylation events not previously attributed to TLR activation were also identified and validated by independent bioassays. This investigation offers insight into the complexity of TLR signaling and more importantly verifies the potential to use bioinformatics approaches to create tools for species-specific kinome analysis based on genomic information.
174

Ultra wideband antenna array processing under spatial aliasing

Shapoury, Alireza 15 May 2009 (has links)
Given a certain transmission frequency, Shannon spatial sampling limit de¯nes an upper bound for the antenna element spacing. Beyond this bound, the exceeded ambiguity avoids correct estimation of the signal parameters (i.e., array manifold crossing). This spacing limit is inversely proportional to the frequency of transmis- sion. Therefore, to meet a wider spectral support, the element spacing should be decreased. However, practical implementations of closely spaced elements result in a detrimental increase in electromagnetic mutual couplings among the sensors. Further- more, decreasing the spacing reduces the array angle resolution. In this dissertation, the problem of Direction of Arrival (DOA) estimation of broadband sources is ad- dressed when the element spacing of a Uniform Array Antenna (ULA) is inordinate. It is illustrated that one can resolve the aliasing ambiguity by utilizing the frequency diversity of the broadband sources. An algorithm, based on Maximum Likelihood Estimator (MLE), is proposed to estimate the transmitted data signal and the DOA of each source. In the sequel, a subspace-based algorithm is developed and the prob- lem of order estimation is discussed. The adopted signaling framework assumes a subband hopping transmission in order to resolve the problem of source associations and system identi¯cation. The proposed algorithms relax the stringent maximum element-spacing constraint of the arrays pertinent to the upper-bound of frequency transmission and suggest that, under some mild constraints, the element spacing can be conveniently increased. An approximate expression for the estimation error has also been developed to gauge the behavior of the proposed algorithms. Through con- ¯rmatory simulation, it is shown that the performance gain of the proposed setup is potentially signi¯cant, speci¯cally when the transmitters are closely spaced and under low Signal to Noise Ratio (SNR), which makes it applicable to license-free communication.
175

Investigation of the photocatalytic lithographic deposition of metals in sealed microfluidic devices on TiO2 surfaces

Castellana, Edward Thomas 15 May 2009 (has links)
The research presented within this dissertation explores the photocatalytic deposition of metal carried out within sealed microfluidic channels. Micro scale patterning of metals inside sealed microchannels is investigated as well as nanoscale control over the surface morphology of the nanoparticles making up the patterns. This is achieved by controlling solution conditions during deposition. Finally, the nanoparticle patterns are used in fabricating a sensor device, which demonstrates the ability to address multiple patches within a sealed channel with different surface chemistries. Also presented here is the construction of the first epifluorescence/total internal reflection macroscope. Its ability to carry out high numerical aperture imaging of large arrays of solid supported phospholipid bilayers is explored. For this, three experiments are carried out. First, imaging of a 63 element array where every other box contains a different bilayer is preformed, demonstrating the ability to address large scale arrays by hand. Next, a protein binding experiment is preformed using two different arrays of increasing ligand density on the same chip. Finally, a two-dimensional array of mixed fluorescent dyes contained within solid supported lipid bilayers is imaged illustrating the ability of the instrument to acquire fluorescent resonance energy transfer data. Additionally, the design and fabrication of an improved array chip and addressing method is presented. Using this new array chip and addressing method in conjunction with the epifluorescence/total internal reflection macroscope should provide an efficient platform for high throughput screening of important biological processes which occur at the surfaces of cell membranes.
176

A Cognitive Phased Array Using Smart Phone Control

Jensen, Jeffrey 2012 May 1900 (has links)
Cognitive radio networks require the use of computational resources to reconfigure transmit/receive parameters to improve communication quality of service or efficiency. Recent emergence of smart phones has made these resources more accessible and mobile, combining sensors, geolocation, memory and processing power into a single device. Thus, this work examines an integration of a smart phone into a complex radio network that controls the beam direction of a phased array using a conventional method, but utilizes the phone's internal sensors as an enhancement to generate beam direction information, Bluetooth channel to relay information to control circuitry, and Global Position System (GPS) to track an object in motion. The research and experiments clearly demonstrate smart phone's ability to utilize internal sensors to generate information used to control beam direction from a phased array. Computational algorithms in a network of microcontrollers map this information into a DC bias voltage which is applied to individual phase shifters connected to individual array elements. To test algorithms and control theory, a 4 by 4 microstrip patch array is designed and fabricated to operate at a frequency of 2.4 GHz. Simulations and tests of the array provide successful antenna design results with satisfactory design parameters. Smart phone control circuitry is designed and tested with the array. Anechoic test results yield successful beam steering capability scanning 90 degrees at 15 degree intervals with 98% accuracy in all cases. In addition, the system achieves successful beam steering operable over a bandwidth of 100 MHz around resonance. Furthermore, these results demonstarate the capability of the smart phone controlled system to be used in testing further array formations to achieve beam steering in 3-Dimensional space. It is further noted that the system extends capabilities of integrating other control methods which use the smart phone to process information.
177

Study on RLS Algorithms in Smart Antenna Systems

Tsai, Guo-Bin 08 January 2004 (has links)
Wireless communication systems are limited in performance and capacity by the major impairments of multipath fading and co-channel interference. Smart antenna can combat the impairments, thereby enhancing the system capacity and alleviating the problem of bandwidth limitation. In general, there are two main types of smart antennas; these are switched beam systems and adaptive array systems. An antenna array, which consists of a group of several antenna elements and digital signal processing units, can form several independent beams in different angles. Smart antennas aim the main beam in the direction of the target mobile user and locate the nulls in the direction of the interfering signals from other mobile users to enhance the signal-to-interference power ratio and system capacity. One of the most important parts in adaptive array antenna systems is the adaptive algorithm to adjust the weights of an array. These algorithms include unconstrained as well as constrained LMS, normalized LMS, structured gradient, RLS, CMA, and conjugate gradient method. In this thesis, we propose a new algorithm based on weight-partition RLS method to reduce the computational complexity. The major concept of our algorithm is decreasing the dimension size of data matrix. Performance and complexity of the proposed algorithm is evaluated and compared with traditional WRLS algorithm.
178

Optimal Quality Control for Oligo-arrays Using Genetic Algorithm

Li, Ya-hui 17 August 2004 (has links)
Oligo array is a high throughput technology and is widely used in many scopes of biology and medical researches for quantitative and highly parallel measurements of gene expression. When one faulty step occurs during the synthesis process, it affects all probes using the faulty step. In this thesis, a two-phase genetic algorithm (GA) is proposed to design optimal quality control of oligo array for detecting any single faulty step. The first phase performs the wide search to obtain the approximate solutions and the second phase performs the local search on the approximate solutions to achieve the optimal solution. Besides, the proposed algorithm could hold many non-duplicate individuals and parallelly search multiple regions simultaneously. The superior searching capability of the two-phase GA helps us to find out the 275 nonequireplicate cases that settled by the hill-climbing algorithm. Furthermore, the proposed algorithm also discovers five more open issues.
179

Manufacturing Technique of QPSFE Fiber Array

Wu, Chun-hsien 29 August 2006 (has links)
For the requirements of high-speed signal transmission has been increasing, the fiber array in the communication system has a lot of advantages which can not be replaced. But the loss of coupling efficiency is a difficult problem as the distance of communication is getting longer and longer. For the sake of solving this problem, the system needs to use optic amplifier for enlarging the coupling efficiency in every long distance. The receiver can receive the correct signal by using optic amplifier. In order to reduce the using amount of optic amplifier for decreasing the cost, producing the fiber array with high coupling efficiency can reach the goal. This paper chooses quadrangular-pyramid-shaped fiber endface (QPSFE) which has better coupling efficiency than flattened-end fiber to research. Among those different manufacturing methods and different precision for fiber array packaging, the research chooses the method of grinding to manufacture the shape of surface. The research can raise the accuracy of manufacture for increasing the coupling efficiency of QPSFE by external equipments.
180

Study of anomalous optical transmission of the subwavelength hole array with depositing dielectric films

Liu, Tung-kai 23 July 2007 (has links)
We operated focus ion beam instrument (FIB) to etch array of cylindrical holes, with the diameter smaller than the wavelength of visible, on the sliver film. The sample was probed with the tungsten light source and the transmission spectrum of visible-NIR range was recorded with traix550 spectrometer with a cooling CCD. The optical extraordinary properties, such as the light can be transmitted through the holes array with the diameter of the hole smaller than the wavelength of the incident light and the enhancement of the efficiency, of the transmission of the subwavelength holes array were discussed. In this study, the factors affected the transmission spectrum of the subwavelength hole array, e.g.: the arrangement of the holes array, the material of the thin film, the diameter of the hole¡Kand so on, were researched. Besides, we modulated the effective dielectric property of the cavity of the subwavelength holes with the thermal evaporation method. It was pointed out that effective dielectric property of the cavity also influenced the optical properties of extraordinary transmission spectrum. We believe that our research was helpful to understand the physical properties of the subwavelength holes array.

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